Overcoming system-size limitations in spin glasses

In order to overcome the limitations of small system sizes in spin-glass simulations, we investigate the one-dimensional Ising spin chain with power-law interactions. The model has the advantage over traditional higher-dimensional Hamiltonians in that a large range of system sizes can be studied. In addition, the universality class of the model can be changed by tuning the power law exponent, thus allowing us to scan from the mean-field to long-range and short-range universality classes. We illustrate the advantages of this model by studying the nature of the spin glass state where our results hint towards a replica symmetry breaking scenario. We also compute ground-state energy distributions and show that mean-field and non-mean-field models are intrinsically different.Comment: 5 pages, 2x2 figures, proceedings of the 2004 SPDSA Conference in Hayama, Japan, July 12 - 15, 200

Social Work handbook

2002 handbook for the Board of Studies in Social Wor

Behavioral and Electrophysiological Measures of Speech-in-Noise Perception in Normal Hearing and Hearing Impaired Adults

University of Minnesota Ph.D. dissertation. July 2017. Major: Speech-Language-Hearing Sciences. Advisors: Dr. Yang Zhang, Dr. Peggy B. Nelson. 1 computer file (PDF): vii, 161 pages.Understanding speech in background noise is difficult for many individuals. Mechanisms responsible for variability in speech-in-noise performance across individuals are not well understood. Electrophysiological measures allow for an examination of the timing and strength of neural responses to speech along the auditory pathway and can be used to explore mechanisms underlying reduced speech perception in noise. This dissertation used behavioral and electrophysiological measures to examine the effects of background noise on the neural coding of speech and to identify potential neural correlates of speech perception in individuals with and without hearing impairment. N1-P2, mismatch negativity (MMN), and P3 auditory event-related potentials (AERPs) and associated event-related cortical oscillations in various frequency bands of interest were collected in response to syllable-level stimuli in noise. Behavioral measures consisted of phoneme discrimination and sentence recognition in noise. Results indicated that in addition to impacting averaged AERP responses, background noise disrupted cortical oscillatory rhythms in response to speech in frequency bands of interest across participants. Results also showed that the effects of background noise and hearing impairment on the neural coding of speech are different at different levels of cortical processing. This work revealed that AERPs and associated cortical oscillations represent potential neural correlates of speech perception in noise in individuals with and without hearing impairment. These findings have potential theoretical and practical implications regarding the use of electrophysiological measures for the assessment and rehabilitation of communication difficulties in background noise

The action of pancreatic desoxyribonuclease. I. Isolation of mono- and dinucleotides

The nature of the products of the action of pancreatic desoxyribonuclease (DNase) upon highly polymerized desoxyribonucleic acid (DNA) has been the subject of numerous investigations. Titrimetric studies (1-5) have revealed that, during the digestion, approximately one secondary phosphate group becomes titratable per 4 phosphorus atoms, which may be interpreted to mean that the products are, on the average, of the magnitude of tetranucleotides. More recently, ionophoretic (9), diffusion (5), and dialysis (10, 11) studies of the digest have suggested that it contains a complex mixture of polynucleotides of a range of magnitudes

A Single Circumbinary Disk in the HD 98800 Quadruple System

We present sub-arcsecond thermal infrared imaging of HD 98800, a young quadruple system composed of a pair of low-mass spectroscopic binaries separated by 0.8'' (38 AU), each with a K-dwarf primary. Images at wavelengths ranging from 5 to 24.5 microns show unequivocally that the optically fainter binary, HD 98800B, is the sole source of a comparatively large infrared excess upon which a silicate emission feature is superposed. The excess is detected only at wavelengths of 7.9 microns and longer, peaks at 25 microns, and has a best-fit black-body temperature of 150 K, indicating that most of the dust lies at distances greater than the orbital separation of the spectroscopic binary. We estimate the radial extent of the dust with a disk model that approximates radiation from the spectroscopic binary as a single source of equivalent luminosity. Given the data, the most-likely values of disk properties in the ranges considered are R_in = 5.0 +/- 2.5 AU, DeltaR = 13+/-8 AU, lambda_0 = 2(+4/-1.5) microns, gamma = 0+/-2.5, and sigma_total = 16+/-3 AU^2, where R_in is the inner radius, DeltaR is the radial extent of the disk, lambda_0 is the effective grain size, gamma is the radial power-law exponent of the optical depth, tau, and sigma_total is the total cross-section of the grains. The range of implied disk masses is 0.001--0.1 times that of the moon. These results show that, for a wide range of possible disk properties, a circumbinary disk is far more likely than a narrow ring.Comment: 11 page Latex manuscript with 3 postscript figures. Accepted for publication in Astrophysical Journal Letters. Postscript version of complete paper also available at http://www.hep.upenn.edu/PORG/web/papers/koerner00a.p